Sea level rise brings added risks to coastal nuclear plants.

• Author: Kenward, Alyson

California's Diablo Canyon power plant is one of nine US nuclear power plants located on the coast. How these coastal plants will withstand sea level rise-related impacts remains unclear. In many parts of the world nuclear reactors are often located near the ocean, due to their requirement for abundant supplies of water for cooling purposes. While tsunamis, like the one that hit Japan in March 2011, aren't a threat everywhere, the sea can pose other challenges. Hurricanes, for example, can push walls of water ahead of them, like the storm surge that did most of the damage to New Orleans when Hurricane Katrina swept through in 2005. In fact, one US nuclear plant has already been dealt a direct hit by a severe hurricane.

But scientists anticipate that in the future, sea level rise will cause hurricanes and their storm surges, as well as flooding caused by other types of storms, to be more severe than during the past few decades. In the wake of the Japanese crisis, which involved a more devastating tsunami than planners anticipated, nuclear analysts in the US are now asking themselves how vulnerable coastal nuclear plants are to a comparable emergency.

"After the events in Japan, we took a hard look at whether our operating facilities are protected, based on current regulations and operating procedures," says Roger Hannah, a senior public relations official with the US Nuclear Regulatory Commission (NRC). Relying on models of expected flood levels and storm surges, along with "real-world experience with hurricanes," the NRC believes all US coastal nuclear facilities are already built to withstand the worst-case storm scenario, Hannah says. On March 23, the NRC also launched an additional two-step review of US nuclear plants, aimed to last about three months.

Of course, the Fukushima Daiichi plant was also designed to withstand what officials considered a worst-case earthquake and tsunami, but that wasn't enough. All of the nine US nuclear plants that are within two miles of the ocean were built at least 30 years ago. But during these three decades the sea has been rising as a result of climate change (not to mention local changes in the geology at some locations, where the land is sinking), and sea level will continue inching up throughout the next century. If the sea is higher to begin with, that means storm surges or tsunamis will pack an extra punch. The worst case, in short, could be worse than anyone imagined when these plants were first built.

In 1992 Hurricane Andrew blew directly over Florida's Turkey Point nuclear plant, cutting off access to external power. The diesel generators supplied back-up power for five days and maintained reactor safety. At Fukushima Daiichi, workers had just a few minutes warning that a tsunami was on its way; at Turkey Point, however, officials...